Blood substitutes are a useful alternative to whole blood in medical applications. They can be used for transfusion when human blood is not available or cannot be administered for religious reasons. They also have novel and promising applications including perfusion of whole organs, preoperative treatment of severely anemic patients, treatment of myocardial and cerebral isochemia to improve oxygen supply, and in combined chemotherapy to enhance the effect of some anticancer drugs. Perfluorochemistry (PFC) emulsions and stroma-free hemoglobin are the two most successful categories of blood substitutes. This proposed workd presents an interdisciplinary approach to the study of PFC blood substitutes. The long-term objectives are to understand the nature and action of the PFC emulsions and to apply this knowledge to prepare better and more stable PFC blood substitutes for medical applications. Spectroscopic and bioengineering techniques will be used to investigate the structure, properties and dynamics of PFC emulsions, and synthetic and electron microscopic methods will be used to complement the physical studies. The specific aims are: (1) To investigate the structure and properties of PFC emulsions and the transport of PFC's through membranes by nuclear magnetic resonance. (2) To assess by constant volumetric flowrate filtration the deformability of human red cells after being exposed to PFC emulsions and the recovery of deformability after the removal of PFC's. (3) To evaluate the ability of PFC's to deliver oxygen across flow constriction as a model of ischemia treatment. (4) To synthesize new fluorinated nonionic surfactants as emulsifiers. (5) To prepare emulsions of PFC's with hemoglobin-linked polyethylene glycol or Pluronic. (6) To use an electron microscope to study the newly prepared emulsions.